Playing Opposites: Why and How Some Pros Go Short on Stocks

Learn how following short interest and other short-selling metrics can help investors can gain valuable insights on companies and markets. selling short
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Key Takeaways

  • Learn how to look at short interest to help find candidates to sell short

  • Understand the relationship between the short interest ratio and susceptibility to a “short squeeze”
  • Consider monitoring short interest metrics, even if you’re an investor with no intentions of short selling

It’s long been taken as “trading gospel” that one should buy stocks low and sell them high. Some traders flip that concept on its head: the short sellers, aka “shorts.” Short selling plays a role in price discovery and liquidity—two components of healthy and efficient markets. It’s also not for everyone, as there are numerous risks, and the mechanics are somewhat complex. But by understanding the basics of short selling and short interest, investors can gain valuable insights on companies and markets.

What is short selling? A short position is essentially a trade that aims to profit from a decline in the value of a share of stock or another asset. That may seem straightforward enough, but short selling stocks can quickly get complicated and risky. Before you consider initiating a short position, it’s important to understand the basics.

But even if you have no intention of becoming a short seller, getting a handle on what short sellers are doing and why, and what that activity might say about a company, industry, or broader market could give you some added perspective as an investor.

How Does Short Selling Work?

Investors who sell short typically borrow stock from a broker and then sell the shares. At some point, the investor must close the short position by buying back the same number of shares and returning those shares to the broker.

If the price drops, the investor can buy back the stock at the lower price and pocket the difference. For example, if a stock shorted at $50 is bought back at $40, the seller realizes a $10 per-share profit (minus transaction costs). On the other hand, a short seller holding a losing position may receive a margin call and be required to put up more money.

Granted, this is an oversimplified explanation of the process of short selling stocks, so before you jump into such a trade, learn about the specifics, such as margin accounts, margin calls, “hard-to-borrow” shares, and other unique characteristics of short selling.

Who Are the Short Sellers?

Short selling tends to belong to the realm of hedge fund traders and other experienced market professionals with large amounts of capital and the capacity to absorb losses when the market moves against them. Typically, a professional trader might sell short if he or she is bearish on a certain stock or industry, or they may be angling for a management shake-up at a company or some other change.

Where Can I Find Information on Short Selling and Short Interest?

Data on short interest—the number of shares outstanding that have been sold short—is available for most U.S. companies listed on major exchanges. The New York Stock Exchange (NYSE) releases a short interest compilation every two weeks.

A glance at these reports often reveals familiar names. Examples might include a pharmaceutical company that’s awaiting regulatory approval for a new drug, or a retailer struggling to develop a viable long-term strategy. During a slump in commodity prices, you might find energy or mining companies ranked among the most-shorted companies.

There are often stories beyond the numbers. Do you see any stocks you’re considering as investments, or that are currently in your portfolio? Think about why other people may have opposing viewpoints. Check recent earnings reports or listen to conference calls for color and context that may have implications for shareholders. Short interest readings are also available when you log in to your account at

How Can Short Selling Be Measured or Quantified?

Market professionals follow key metrics, including “shorts as a percentage of float,” which reflects the number of short-sold shares in proportion to the “float,” or the total number of shares available for trading in the public markets.

Most stocks have a small amount of short interest, usually in the single digits. The higher that percentage goes, the greater the bearish sentiment might be surrounding that stock. If the float reaches 10% or higher, some market pros consider it a red flag. See figure 1.

FIGURE 1: INTERESTING? To view short interest as a percentage of available float, log in to your account at, look under Research & Ideas > Stock Profile, and type in any symbol. At 23.25%, the short interest percentage in this example stock is quite high relative to the broader market. Source:

“Days to cover,” also referred to as the short interest ratio, indicates how long it would take to cover, or buy back, all the shorted shares. This is calculated by dividing the number of shares sold short by the average daily trading volume, and some view it as a measure of the future buying pressure on a stock. Some short sellers look for about seven days to cover or fewer before shorting a stock.

What About the “Short Squeeze?”

A short squeeze can happen when bullish news pushes a stock price higher, prompting short sellers to head for the exits all at once. As the shorts scramble to buy back and cover losses, upward momentum builds upon itself and the stock can move sharply higher. The longer the days to cover, the more pronounced this effect can be.

Short interest can also be applied alongside chart indicators, such as moving averages, for signals on when it may be time to get out of a stock. For example, a combination of high short interest and a drop below the 52-week low or the 200-day moving average might indicate "look out below."

What Might Short Selling Activity Indicate?

Across the broader market, short interest has not been historically high in recent years. Near the end of 2018, for example, short interest in the S&P 500 was about 2.17% of shares outstanding, down from 2.3% in late 2017, according to FactSet Research Systems. Total NYSE short interest at the end October 2018—a quite volatile month—was about 16 billion shares, down from 16.4 billion a year earlier.

During the heady days of the 2008-09 financial crisis, short interest topped 19 billion shares. A couple years later, as markets recovered and began their multi-year march higher, it fell to below 12 billion shares.

The short answer? Even if you have no intention of short selling stocks, you might find value in understanding, and keeping an eye on, short selling metrics and dynamics.


Key Takeaways

  • Learn how to look at short interest to help find candidates to sell short

  • Understand the relationship between the short interest ratio and susceptibility to a “short squeeze”
  • Consider monitoring short interest metrics, even if you’re an investor with no intentions of short selling

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